Appeals Court Rules Against Amgen in Patent Case

A U.S. federal appeals court said Thursday Regeneron Pharmaceuticals Inc. and partner Sanofi SA can continue selling their cholesterol drug, dealing a blow to rival Amgen Inc., which had accused the companies of violating its patents.

Judge Sharon Prost of the U.S. Court of Appeals for the Federal Circuit in an opinion called for a new trial and allowed the companies' drug, Praluent, to remain on the market for now. The court in February allowed the companies to continue selling Praluent while the appeal was ongoing.

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Mizuho analyst Salim Syed called the ruling a "modest negative" for Amgen. "The bottom line here is that there is no definitive winner or loser yet in this litigation," wrote Mr. Syed in a research note Thursday. While the ruling hurts Amgen by keeping Praluent on the market for at least another year, it doesn't mean the drug won't eventually be taken off the market, he wrote.

Regeneron shares have been halted Thursday on the news. Amgen shares fell 1.9%, while ADRs in Sanofi rose 0.2%.

Praluent and Amgen's competing drug Repatha, each approved for sale in 2015, belong to a new class of cholesterol fighters known as PCSK9s.

Analysts initially expected the drugs to be multibillion-dollar sellers, but health-insurance plans have restricted use because they can cost $14,000 per patient each year.